Question

a scientist discovers a dna - based test for one allele of a particular gene. this and only this allele, if homozygous, produces an effect that results in death at or about the time of birth. which of the following statements describes the best use of this discovery?
follow the segregation of the allele during meiosis.
screen all newborns of an at - risk population.
introduce a normal allele into deficient newborns.
design a test for identifying heterozygous carriers of the allele.

Explanation:

The scientist has discovered a DNA - based test for an allele that is lethal when homozygous. The best use of this discovery would be to screen newborns of an at - risk population. This is because screening allows for early identification of those with the homozygous condition (who will die at or around birth) and also helps in identifying heterozygous carriers (if the test can be adapted). Introducing a normal allele into deficient newborns is gene therapy which is a complex process and not directly related to the immediate use of the DNA - based test. Following the segregation of the allele during meiosis is more of a research - level genetic study rather than a practical application of the test. Designing a test for heterozygous carriers is a possible use, but the first step with a test that can identify the homozygous (lethal) condition is to screen the at - risk population (newborns) to prevent the negative outcome (death) as much as possible (by providing appropriate care, though in the case of a lethal allele at birth, it may be more for documentation and family counseling) and also to identify the presence of the allele in the population.

Answer:

Screen all newborns of an at - risk population.